Predictors of inter-proximal and midfacial recession following single implant treatment in the anterior maxilla: a multivariate analysis

Purpose A number of factors have been associated with soft tissue recession following single implant treatment. However, given the cross-sectional design of most of these studies and crude associations based on univariate analyses, such factors may only be considered risk indicators. The objective of the present retrospective cohort study using multivariate analyses was to identify predictors of recession. Material and Methods Patients who had been treated by two periodontists and two prosthodontists in 2006 and 2007 for a single implant in the anterior maxilla were re-examined in 2009 and their records were scrutinized. Subjects treated via flap surgery with and without ridge re-contouring were considered. Outcome variables were inter-proximal and midfacial recession. Explanatory variables included demographic data, the surgical approach and a number of local factors that were evaluated on radiographs taken pre-operatively or at permanent crown installation (baseline). Results Data pertaining to 97/115 (60 females, 37 males; mean age 51, SD 13, range 2380) patients were available for evaluation. Significant bone loss was observed between baseline and re-examination at the implant surface (0.20.3 mm, p < 0.001) and tooth surface (0.30.5 mm, p < 0.001). Surgery with ridge re-contouring demonstrated 0.2 mm additional bone loss at the distal tooth surface when compared to surgery without ridge re-contouring (p = 0.034). This could be explained by a disparity in possible papilla-opening procedures (three versus one or two). As a result, regression analyses identified surgery with ridge re-contouring as a predictor of inter-proximal recession (OR = 3.4). Pre-operative bone level at the tooth surface was another predictor of inter-proximal recession (OR = 2.1). Recession of the distal papilla was also affected by a missing contact point (OR = 221.9), the implant-to-tooth distance (OR = 0.3) and the distance of the bone peak to the contact point (OR = 2.9). Midfacial recession was only associated with a buccal shoulder position (OR = 17.2). Conclusions To optimize soft tissue levels around single implants, clinicians should limit papilla-opening procedures and pay utmost attention to a correct implant and contact point positioning.